HID: hid-sony.c: Use devm_ api to simplify sony_register_touchpad()

Using devm_ calls, the resources of the Sony game devices's features are
tied to the main device handle, making it easier to handle errors and
teardown inside the device driver. Altogether, this reduces complexity
of the driver source.
Signed-off-by: Hanno Zulla <kontakt@hanno.de>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>